A method of generating a multi-level signal having one of three or more voltage levels that are different from each other, the method including: performing a first voltage setting operation in which first and second voltage intervals are adjusted to be different from each other, wherein the first voltage interval represents a difference between a first pair of adjacent voltage levels and the second voltage interval represents a difference between a second pair of adjacent voltage levels; performing a second voltage setting operation in which a voltage swing width is adjusted, the voltage swing width representing a difference between a lowest and a highest voltage level among the three or more voltage levels; and generating an output data signal that is the multi-level signal based on input data including two or more bits, a result of the first voltage setting operation and a result of the second voltage setting operation.

An apparatus and method for providing a decision feedback equalizer are disclosed herein. In some embodiments, a method and apparatus for reduction of inter-symbol interference (ISI) caused by communication channel impairments is disclosed. In some embodiments, a decision feedback equalizer includes a plurality of delay latches connected in series, a slicer circuit configured to receive an input signal from a communication channel and delayed feedback signals from the plurality of delay latches and determine a logical state of the received input signal, wherein the slicer circuit further comprises a dynamic threshold voltage calibration circuit configured to regulate a current flow between output nodes of the slicer circuit and ground based on the received delayed feedback signal and impulse response coefficients of the communication channel.

Embodiments are disclosed for facilitating an end-to-end link channel with one or more lookup tables for equalization. An example system includes a first transceiver and a second transceiver. The first transceiver includes a clock data recovery (CDR) circuit configured to receive communication data from a switch and to manage a lookup table associated with equalization of the communication data. The first transceiver also includes a first driver circuit communicatively coupled to the CDR circuit and configured to generate an electrical signal associated with the communication data. The second transceiver includes a second driver circuit, communicatively coupled to the first transceiver, that is configured to receive the electrical signal from the first transceiver and to modulate a laser source based on the electrical signal to generate an optical signal via the laser source.

A transition enforcing coding (TEC) receiver includes a first delay line circuit, a transition detection circuit, and a data sampling circuit. The first delay line circuit delays a plurality of vector signals to generate a plurality of delayed vector signals, respectively. The transition detection circuit detects a transition of at least one specific delayed vector signal among the delayed vector signals. The data sampling circuit samples the vector signals according to a sampling timing determined based on an output of the transition detection circuit.

A device and method for a receiver configured to perform timing recovery decoupled feed-forward equalizer (FFE) adaptation. The receiver device can include an analog front-end (AFE) device, which is coupled to a time-interleaved (TI) interface. The TI interface is coupled in a timing recovery feedback loop to FFE equalizers, a digital signal processor (DSP), a delay timing loop (DTL) device, and a clock device, which feeds back to the TI interface. The DSP has an additional pathway to the FFE equalizers, which has an additional pathway to the DTL device. The DTL loop is equipped with an interleave specific enable/disable vector Q[1:N] that can turn on/off the contribution of the specific time interleave errors to the timing recovery loop, which allows the FFE adaptation process to be decoupled from the timing recovery loop.

A system for communicating information between circuits is described. A transmit circuit provides pulse-amplitude-modulation (PAM) signals via a communication channel to a receiver. A circuit in the receiver determines digital values from the received signals using a time-varying threshold voltage, which varies during the bit-time. This approach may compensate for inter-symbol interference (ISI) to increase the voltage and timing margins of the system.

Decision feedback equalization (DFE) is used to help reduce inter-symbol interference (ISI) from a data signal received via a band-limited (or otherwise non-ideal) channel. A first PAM-4 DFE architecture has low latency from the output of the samplers to the application of the first DFE tap feedback to the input signal. This is accomplished by not decoding the sampler outputs in order to generate the feedback signal for the first DFE tap. Rather, weighted versions of the raw sampler outputs are applied directly to the input signal without further analog or digital processing. Additional PAM-4 DFE architectures use the current symbol in addition to previous symbol(s) to determine the DFE feedback signal. Another architecture transmits PAM-4 signaling using non-uniform pre-emphasis. The non-uniform pre-emphasis allows a speculative DFE receiver to resolve the transmitted PAM-4 signals with fewer comparators/samplers.

A multi-PAM equalizer receives an input signal distorted by inter-symbol interference (ISI) and expressing a series of symbols each representing one of four pulse amplitudes to convey two binary bits of data per symbol. High-order circuitry resolves the most-significant bit (MSB) of each two-bit symbol, whereas low-order circuitry 115 resolves the immediate least-significant bit (LSB). The MSB is used without the LSB for timing recovery and to calculate tap values for both MSB and LSB evaluation.

Transmitters and communication systems are disclosed. In one example, a transmitter includes first to third serializers that generate first to third serial signals; a first output section configured to set a voltage of a first output terminal; a first output control circuit configured to control an operation of the first output section on the basis of the first serial signal and the second serial signal; a second output section configured to set a voltage of a second output terminal; a second output control circuit configured to control an operation of the second output section on the basis of the third serial signal and the first serial signal; a third output section configured to set a voltage of a third output terminal; and a third output control circuit configured to control an operation of the third output section on the basis of the second serial signal and the third serial signal.

Methods, systems, and devices for data inversion techniques are described to enable a memory device to transmit or receive a multi-symbol signal that includes more than two (2) physical levels. Some portions of some multi-symbol signals may be inverted. A transmitting device may determine to invert one or more data symbols based on one or more parameters. A receiving device may determine that one or more data symbols are inverted and may re-invert the one or more data symbols (e.g., to an original value). When receiving or transmitting a multi-symbol signal, a device may invert or re-invert a data symbol by changing a value of one bit of the data symbol. Additionally or alternatively, a device may invert or re-invert a data symbol of a multi-symbol signal by inverting a physical level of the signal across an axis located between or associated with one or more physical levels.